Power transmission



July'25, 1944. J; ROBINSON 2,354,273

I POWER- TBANSMISSION Fild Dec. 16, 1940 v INVENTOR JAMES ROBINSON I08 BY 44 log,

5 I28 B I I40 v circuit disclosed iii-Figure 1.

Patented July 25, .1944

POWER TRANSMISSION James Robinson, Detroit, Mich, assignor to Vickers Incorporated, Detroit, Mich, a corporation of Michigan Application December 16,1940, Serial No. 370,364

Claims. (Cl. 242-75) This invention relates to power transmissions, particularly to those of the'type comprising two or more fluid. pressure energy translating devices, one of which may function as a pump and another as a fluid motor.

The invention is more particularly concerned with a hydraulic power transmission system adapted for use with a strip material handling device of the type where the strip material is passed back and forth between two reels and is alternately uncoiled from the first reel and recoiled onto the second reel and then uncalled from the second reel and recoiled onto the first reel during the reverse movement of the strip. In the application of Ferris T. Harrington and James Robinson, Serial No. 357,896, there is disclosed a power transmission system particularly adapted for reeling strip material 011' from one reel and onto another. In the device there disclosed the'operation is always in one direction, and it is impossible to utilize the system for machines of the type where the strip is coiled and uncoiled alternately in opposite directions.

It is an object of the present invention to provide a hydraulic power transmission system in which the power conserving advantages of the aforesaid copending application may be obtained with a strip. material handling device operating alternately in either direction.

A further object is to provideimproved pressure responsive regulating means for a variable displacement fluid pressure energy translating device wherein the action may be selectivly reversed to either increase the displacement of the device with increases in pressure or to decrease the displacement of the device with increases in pressure.

Further objects and advantages of the present invention will be apparent from the following 4 description, reference being had to the accompanying drawing wherein a preferred form of the present invention is clearly shown.

In the drawing: 1

Figure 1 is a diagrammatic view of a 'power transmission system incorporating a preferred form of the present invention.

Figure 2 is a sectional view of a pressure responsive regulating mechanism embodied in the A sectional machine for operating on strip material is illustrated in the drawing and, by way of example, comprises a rolling stand Ill which constitutes a driving section. The details of the rolling stand form no part of the present 56 invention, it being understood that many other mechanisms for operating on strip stock and at the same time moving it longitudinally from right to left or from left to right could equally well form the driving section of the machine. A supply reel is indicated at I2 comprising a coil of strip l4 which, as disclosed, is partly unwound so that a not section of strip l6 extends through the driving section Hi to a take-up reel l8 where the strip is again reeled into a coil 20. The roll stand ID has a drive shaft 22 whic is driven'by means of a reversible drive gearing 24 from an electric motor 28. The reversible gearing 24 has a shift lever 28 which may be operated by means of a piston 30 reciprocable within a cylinder 32;

lever 28 will be shifted clockwise to reverse the gearing 24.

Each of the reels l2 and leis adapted to be selectively driven by or to drive one of a pair of hydraulic displacement devices 34 and 36, each of which is adapted to function either as a pump or as a motor. The devices 34 and 36 are of the variable displacement type and, as illustrated in the drawing, may have a swinging yoke 38 and 40, respectively, the angular positionof which determines the stroke or displacement of the device. Pumps and motors of this class are well known in the art such, for example, as illustrated in Thoma Patent No. 1,931,969. The devices 34 and 36 are each provided with a pressure responsive displacement regulator t2 and 44, respectively, the details of I which are shown more clearly in Figure 2.

Connected in driving relation with the electric motor 26 is a secondpair of hydraulic displace ment devices 48 and 48 which may be similar to the devices 34 and 36 with the exception that they are not provided with pressure responsive displacement regulators. They may be provided, however, with-manual controls 50 and 52 for altering their displacement from time to time to provide for the use of reels of greater orlesser core diameter. In the circuit shown, and later to be described, the device 46 is so connectedas to always act as a fluid motor and to assist the electric motor 28 in driving the roll stand Ill. The device 48, however, is so connected as to always operate as a pump and so absorb power from the electric motor 26, or from the fluid motor 48. e F

The devices 34 and 36 are connected by conduits 54 and, with the Thus, when pressure is applied to the lower end of the cylinder 32, the

I d and center ports, seamen: ed? .tti ZZiiSQ'i' sit? in Due H5130 aria grieve-xii ,cgoti fe. "'31) -::-".-'*Ti* r v 2' assasve respectively, of a conventional pilot-operated, four-way, reversing valve 58. The two intermediate ports of the valve are connected by conduits 60 and 62 with the devices 46 and 48. respectively. Interpused in the conduits 80 and 82 are a pair of back pressure valves 84 and 68 of similar construction and arranged to block flow through their respective conduits except when a predetermined pressure has been reached in the conduit on one side of the valve.

The valves shown in the drawing are similar to that shown in Herman Patent No. 2,200,824, although it will be understood that any other suitable type of back pressurevalve may be utilized at this point in the circuit. Since the flow in conduit 80 is always from the top to the bottom of the page and the flow in conduit 62 is in the opposite direction, the valves are positioned in the conduits in reverse relation so that valve 84 will open in response to pressure developed in the upper part of conduit 80 while valve 88 will open in response to pressure de veloped in the lower part of conduit 62.

Also interposed in conduit 82 is a relief valve 88 which may be similar to that illustrated in Vickers Patent No. 2,043,453, and serves to limit the maximum pressure against which the unit d8 must pump. The valve 68 also serves as a starting and stopping control by means or a pilot venting connection 10 leading from the control chamber of the valve 88. The connection 18 leads to a two-way pilot valve I2 for the purpose oi selectively blocking or opening a connection to tank through conduits I4 and 18. The conduit it also communicates with one side 01' the hydraulic displacement unit 88 while a corresponding conduit I8 communicates with one side of the unit 34. Similarly the units 48 and 48 are provided with tank conduits 88 and 82.

It will be seen that the hydraulic units and circult thus far described constitute a coupling circult between th reel i2 and the reel i8 with a synchronizing connection to the roll stand it. Thus, assuming the strip ii to be moving in the direction of the arrows, unit 34 will be operated as a pump withdrawing oil from the tank through conduit 18 and delivering it through conduit I4, valve 84 and conduit It tothe unit 48 driving the $8 in conduit 80 acts to maintain a predetermined back pressure on whichever oi the units 14 and 36 is operating as a pump and thus insures against overrunning or coasting. Similarly, the valve 86 imposes a predetermined back pressure in the conduit 82 between it and the pump unit 38 for the purpose of maintaining a supply of pilot pressure available at the branch conduit 84 which is always in communication with the bottom portion of conduit 52.

Conduit 84 delivers this pilot fluid to the pressure port of a conventional rotary four-way pilot valve 86, the tank port of which is connected to the tank by a conduit 88. The valve 88 in the position shown connects pilot pressure conduit 86 with a conduit 90 and connects the tank conduit 88 with a conduit 92. When the valve is shifted forty-five degrees clockwise, pilot pressure is connected to conduit 82 while conduit 88 is connected to tank. The conduits 90 and 92 provide parallel pilot connections, first, to the opposite ends of cylinder 32, and then to the pilot operating chamber of the valve 58 as well as to the pilot operating chambers of a pair oi pilot-operated four-way valves 84 and 98 which serve to ccntrol the action of displacement regulators 42 and 54. These conduits also connect with certain chambers 98 and I00 in each of th displacement regulators M and 44.

Thus, with the valve 88 in the position shown in the drawing, pilot pressure in conduit 90 holds piston 30- down, holds valve 88 to the left and holds valves 94 and 98 to the right and maintains pressure in the chamber 88 of regulator 42 and in the chamber III) of regulator 44. When the valve 88 is shifted to its opposite position,

exactly opposite conditions are set up in each' of the parts mentioned.

Referring now to Figure 2-, the section of the regulator 44 is there illustrated on a larger scale. and, since the the regulator 42 is identical, the

construction of only one will be described. Thus latterasamotor-andtheoilto the" tank ll through conduit 80. Thus, depending upon the relative displacements of units 84 and 4 4,thereel i! willbeooupledtothemotorfl whichinturniseouiiedtothe roll the regulator comprises a cylindrical body "I having an enlarged bore I 84, the opposite ends of which form the chambers 88 and Ill. At its left portion the body III is provided with a smaller bore III in which a bnlanoedpiston II. is reciprocably mounted. The latter carries a rod Ill projectingthroughthelettendofthebods- J02 andwhichisconnectedbymeansotalink' ll! withthe l ke 48 otnnitll. Atits righthand side the piston III has 0. correspondingrod H4 whichis provided with abortion III of reduced diameter. At its l8hthand end the rod ll4isprovidedwithaportion lllotnormal diameter and whichmayb'etormedas a separate piece and assembled to the main portion of-rod lllasbytl'ireadingthereonandwhichisslidable in a small bore. in an end cap in which closes the rlzhthand end of bore I84. A small end cap I24 closes the end oi. bore I28 and may be provided with a breather hole I18. Mounted againsttheshouldersattheoppositeendsofthe reduced portion 8 are a pair of washers III and I88 forming abutments' for a on springifl.

Slidableinthebore li4lsaspringabutment shitting member I84 formed as a diiferential pism is shifted and maintained in the position 11- lustrated by pilot pressure admitted to chamber I88. When pilot pressure is admitted to chamber 88, the member I34 shifts to the right 1 ports of valves 84 and 88 are connected by conduits I82 and I54 with the conduits 54 and 58, respectively. The end ports of these valves are connected by conduits I58 and I88 with small spring-loaded ball valves I88 and I82 which act as pilot relief valves opening in response to a predetermined pressure which depends upon the setting 'ofthe adjustable spring therein. -The discharge side of the valves I 88 and I82 is connected to tank by conduits I84 and I88.

The parts are shown in the drawing in thecondition when the device is in operation with motor 28 running and with the roll. stand I8 pulling, the strip I8 from right to left in the direction of the .arrows. The flow of fluid in the main coupling circuit is as previously described; and the pressure in the pilot c rcuit is maintaining all of the pilot control members in the position shown in the drawing. The adjusted position of the stroke varying yokes of the units 48 and 48 remains fixed as determined by the original diameter of the reel cores, while the stroke position of the yokes 38 and 48 is determined by the pressure conditions in conduits 84 and 58 due to the action of the regulators 42 and 44, respectively. t

With the spring abutment shifting member I34 of. regulator 42 shifted to its lefthand position, as illustrated, and with the valve 94 in its righthand position, it will be seen that the fluid pressure generated in line by unit is transmittedthrough conduit I52 to conduit I48 and accordingly acts on the lefthand face of the piston I88 of regulator 42. Due to the greater area over which-member I34 is exposed to the pres, sure in chamber 88, the member I34 remains stationary regardless of the pressure developed in chamber I42. It will be seen that the pump delivery pressure on the lefthand' face oi piston I88 acts in a'direction tending to reduce the displacement of unit 34 and also that the spring I32 will be compressed by spring washer I38 which moves to the right with piston. rod portion II8 whenever piston I88 moves to the right. Thus relief valve I88 again closes or atleast closes sufliciently to pass no more oil than passes through conduit I58. Thus, as the pressure in conduit 54 tends to rise, the stroke or displacement of unit 34 is correspondingly reduced.

Since the unit 481s driven at constant speed by the motor 28 and since its displacement is fixed,

the unit 34 will have to turn at ahi'gher speed as its stroke is progressively decreased in order to pass the same quantity of fluid as before. Consequently the speed of reel I2 is progressively increased as is necessary from the fact that its 7 diameter is decreasingby reason'of progressive layers of strip being unwound therefrom while the lineal speed of the strip is'maintained constant by the roll stand I8. The progressive decreaseof displacement or stroke at unit 34 also acts to decrease the torque reaction which is maintained by unit 34 on the reel I2 which also is necessary due to the decreasing diameter of the coil I4 while the tension in strip I8 is maintained constant.

' It is an inherent characteristic of any variable displacement hydraulic unit that, when acting as a pump against a fixed delivery pressure, the torque required to drive the pump decreases progressively with decreases in displacement. This decrease in torque and the previously mentioned increase in speed of the unit 34 and reel I2 is a hyperbolic relationship so that the product of torque and speed remains constant as is fully explained in the aforesaid copending application of Harrington and Robinson.

It will be noted that the work done in unwinding strip from the coil I4 against a constant back tension is restored to the system at motor 28 instead of being wasted in the form of heat as would be the case if the usual friction brake -were applied to the supp y reel shaft I2.

At-the same time that the above-described action is occurring at the supply reel I2, the takeup reel I8 is being driven by the unit 36 acting as a motor. abutment shifting member I34 has been shifted to its opposite position so that the line pressure acting in chamber I44 tends to increase the vdilsplacement or stroke oi the member 38. Thus, as the pressure in conduit 58tends to rise due to the progressively increasing diameter, of coil 28, yoke member 48 will be progressively shifted to the right. This has the effect of correspondingly reducingthe speed at which reel I8 'is driven by the fixed displacement pump 48 and, at the same time, progressively increases the torque applied by .the'unit 38 to the reel I8. Thus, the action of unit 38 in driving the reel is regulated to corthe spring I32 biases the piston I88 and yoke 38.

to the left against the pressure in the chamber I42. The line pressure is, however, also transmitted to the chamber I44 on the righthand side of the piston I88 through the restricted passage I88, and, so long as the relief valve I88 remains oil'to the tank out of chamber I44 than can now into chamber I44 through the restricted passage 8". Accordinglmpiston I83 will move to the right reducing the displacement of unit 34 until the pressure in line 54 drops to the point where respond to the requirements of the progressively increasing coil diameter at 28, while maintaining constant tension in the strip section ll between coil 28 and roll stand I8 and while also maintaining constant linear speed of the strip.

It may be observed that, neglecting losses in the'system, the power required to drive pump 48 is equal to the power delivered by motor 48 so that the only work necessary for motor 28 to do is' to make up the losses in the reel coupling hydraulic system, and to supply the power requiredto operate roll stand I8. when the length of strip has been fully unwound from coil I4 and'fully wound onto coil 28, the pilot. valve ll-may be shifted to reverse the pilot connections, shifting the piston 38 to reverse the direction ofdrive at roll stand I8 and also shifting the three pilot-operated valves 88, 84 and 88 as well as the two spring abutment shifting mem- In this case, however, the spring bers B6 of the two stroke regulators. The action underthese conditions is exactly corresponding to that previously described except that the direction of strip movement is reversed and the unit 34 now acts as a hydraulic motor driven by the pump 48 while the unit 36 acts as a pump to drive the fluid motor.

While the form of embodiment of the invention. as herein disclosed constitutes a preferred form, it is to be understood that other forms might be adopted, all coming within the scope of the claims which follow.

What is claimed is as follows:

1. In a strip material handling device comprising a pair of reels each adapted to alternately act as a supply reel or a take-up reel as the strip is passed back and forth between the reels, a pair of constant pressure, variable volume, hydraulic displacement devices, one connected in driving relation to each reel, constant volume, variable pressure, hydraulic displacement means driven at a speed proportional to the linear speed of the strip, a circuit connecting said displacement means to receive and deliver all of the fluid passing through each constant pressuredisplacement device, and means for reversing the direction of strip motion.

2. In a strip material handling device comprising a pair of reels each adapted to alternately act as a supply reel or a take-up reel as the strip is passed back and forth between the reels, a pair of constant pressure, variable volume, hydraulic displacement devices, each device having a pressure responsive volume regulator, one connected in driving relation to'each reel, constant volume, variable pressure, hydraulic displacement means driven at a speed proportional to the linear speed of the strip, a circuit connecting said displacement means to receive and deliver all of the fluid passing through each constant pressure displacement device, and means for reversing the direction of strip motion andsimultaneously reversing the action of both volume regulators.

3. A strip material handling device comprising a supply reel from which the strip is to be unwound and a take-up reel onto which the same strip is to be wound, a pair of constant pressure, variable volume, hydraulic displacement devices, one connected in driving relation to each reel,

a pair of constant volume, variable pressure, hy-

draulic displacement devices, means for driving the last-mentioned devices at a controlled speed, and fluid supply and return conduits connecting each constant pressure device with a separate one of the constant volume devices. 4

aaeaare 4. In a sectional machine for operating on strip material the combination of a driving section having means for engaging the strip and moving it longitudinally, power means for driving the driving section at a controlled speed, a supply reel section from which the strip is unreeled by the pull of the driving section, a take-up reel section onto which the strip is reeled after leaving the driving section, and means for controlling the tension of the strip between said three sections comprising variable displacement fluid pressure energy translating units, one coupled in driving relation to'eachreel section, hydraulic fluid pressure energy translating mechanism driven with the driving section, a hydraulic circuit connecting said units with said mechanism, pressure responsive means for regulating the displacement of each of said units, means for reversing the driving section to cause the strip to pass from the take-up section to the supply section,

and means for reversing the action of said pressure responsive means whereby each unit will be regulated to increase its displacement with increases in pressure during winding operation and to decrease its displacement with increases in pressure during unwinding operation.

5. In a sectional machine for operating on strip material the combination of a driving section having means for engaging the strip and moving it longitudinally, power means for driving the driving section at a controlled speed, a supply reel section from which the strip is unreeled by the pull of the driving section, a take-11p reel section onto which the strip is reeled after leaving'the driving section, and means for controlling the tension of the strip between said three sections comprising variable displacement fluid pressure energy translating units, one coupled in driving relation to each reel section, hydraulic fluid pressure energy translating mechanism driven with the driving section, a hydraulic circuit connecting said units-with said mechanism, pressure responsive means for regulating the displacement of each of said units, means for reversing the driving section to cause the strip to pass from the take-up section to th supp y section, means for reversing the action of said pressure responsive means whereby each unit will be regulated to increase its displacement with increases in pres-.

sure during winding operation and to decrease its displacement with increases in pressure during unwinding operation, and means for simultaneously actuating both said reversing means.

JAMES ROBINSON. 

